This invention relates generally to fluid pressure measurement, and more particularly, to a new and improved pressure diaphragm by means of which the pressure in a fluid line can be sensed. The invention has particular application in connection with instrument systems for administering parenteral fluids to the human body.
The administration of parenteral fluids to human patients conventionally involves use of a solution administration set. The set typically is a disposable plastic product, and comprises a drip chamber adapted to be connected to a fluid source, a length of tubing extending from the chamber to the patient and a valve mechanism, such as a roller clamp on the tubing.
In recent years, a variety of mechanical and electrical monitoring systems, controllers and infusion pumps have been developed to accomplish the tasks of sensing and regulating the rate of fluid flow into the human body. Such apparatus may include an electromechanical output device for manipulating the tubing of a conventional administration set in a prescribed manner, as by using a series of cam followers that sequentially massage the tubing and generate a peristaltic pumping action. For use in other apparatus, the tubing may include a syringe which is cyclically driven by the electromechanical output device through alternate fill and pump strokes to draw and deliver precise amounts of fluid from the fluid source to the patient. Alternatively, instead of a conventional administration set, a set comprising a length of tubing extending from a self-contained syringe to the patient may be used in an apparatus designed for a single controlled pump stroke to deliver the fluid contained in the syringe to the patient.
A common feature of each of these apparatus is the capability of developing positive pressure in the tubing. Some of the apparatus have also been capable of activating alarms when an out-of-limit condition exists, thus freeing medical personnel to some extent for other duties.
However, while such apparatus have generally served their purpose, there has been a need for an effective, safe and reliable means of sensing fluid pressure in the tubing leading to the patient. Specifically, concerns have been raised about the capability of monitoring and controlling the fluid pressure developed in the tubing by such positive pressure electromechanical devices.
Hence, those concerned with the development and use of fluid administration systems, and particularly those concerned with the design of parenteral administration systems, recognize the need for improvement in devices for sensing fluid pressure.